Mechanical interlock



Sept. 15, 1964 J. HAYDU ETAL MECHANICAL INTERLOCK 4 Sheets-Sheet 1 Filed March 13, 1961 INVENTORS JOHN L. HAYDU LELAND E. LAWRENCE mag/KM ATTORNEY Sept. 15, 1964 J. HAYDU ETAL 3,149,210

MECHANICAL INTERLOCK Filed March 13. 1961 4 Sheets-Sheet 2 INVENTORS 3 1 mm m M LELAND. E. LAWRENCE BY M ATTORNEY a A m L wa m a1 a @m M m 1 n LW 0 IA F Z N/ m Se t. 15, 1964. J. L. HAYDU ETAL MECHANICAL INTERLOCK 4 Sheets-Sheet 3 Filed March 13, 1961 S R O TU ND Ev VA NH L N H O J LELAND E. LAWRENCE ATTORNEY Sept. 15, 1964 J. L. HAYDU ETAL MECHANICAL INTERLOCK 4 Sheets-Sheet 4 Filed March 13, 1961 INVENTORS JOHN L. HAY DU LELAND E. LAWRENCE ATTORNEY United States Patent 3,149,210 MECHANECAL INTERLQCK John L. Haydn, Milwaukee, and Leland E. Lawrence,

Wauwatosa, Win, assignors to Mien-Bradley Company, Milwaukee, Wis, a corporation of Wisconsin Filed Mar. 13, 1961, Ser. No. 95,216 8 Claims. (Cl. zen-50 This invention relates to an interlock mechanism for electromagnetically actuated switches and similar devices characterized by having a movable actuator, and it more specifically resides in a mechanical interlock having a pivoted rocker for disposition between a pair of associated switches or devices being interlocked together with a pair of levers each pivotably supported intermediate its ends with one end acting as a track follower for engagement with a bearing surface on said rocker and the opposite free end being in the path of travel of the actuator of one of the devices being interlocked whereby movement of the actuator of one device against the free end of the associated lever pivots such lever so as to move the track follower end against the rocker to pivot the rocker and thereby hold the free end of the second lever in a blocking position with respect to the actuator of the second device to prevent movement of such actuator, said interlock mechanism of this invention being further adapted to interlock a plurality of devices through the provision of multiple rockers and a linkage joining such rockers.

In the customary use of a pair of electromagnetic motor starting switches for either a two speed or reversible motor each switch connects motor windings directly across the power lines and means must be provided to preclude simultaneous closing of the switches. Hence, it is a requirement in the use of electromagnetic switches for reversing control and for multiple speed control of motors that the switches be positively interlocked to prevent the completion of a circuit through more than one switch at any given instant. The interlock should also be capable of preventing closure of one switch before the extinguishment of the are drawn by the contacts of the companion switch when it is being opened. To this end, the interlock of this invention provides positive, mechanical restraint against the closing of more than one switch at any one time, and further prevents contact engagemen-t by a switch prior to the complete contact disengagement of a switch being opened.

It is, therefore, an object of this invention to provide an interlock for electromagentic switches and similar devices which prevents closure of more than one such switch or device at any one time by a direct mechanical blocking.

It is another object of this invention to provide a mechanical interlock which is so constructed that its application to associated switches requires no alteration in their design or construction.

It is still another object of this invention to provide a mechanical interlock which is simple to assemble and which is not connected directly to the associated switches or devices being interlocked.

It is a further object of this invention to provide a mechanical interlock of simple design and construction which is adjustable for proper positioning relative to switch actuators being interlocked.

It is still a further object of this invention to provide a mechanical interlock which is adapted for interlock of a plurality of switches.

The means for accomplishing the foregoing and other objects and advantages of this invention will appear in the following description. In the description reference is made to the accompanying drawings which form a part hereof, and in which there is shown by way of illustration, and not of limitation, specific forms in which this invention may reside.

In the drawings:

FIG. 1 is a view in elevation of one embodiment of the interlock mechanism of this invention as applied to a pair of electromagnetic switches and it shows one of the associated switches in closed position,

FIG. 2 is a view in section taken along the line 2-2 shown in FIG. 1,

FIGS is a view partially in section taken along the line 3-3 shown in FIG. 4,

FIG. 4 is a view in section taken along the line 4-4 shown in FIG. 3 with a portion of one lever broken away to show the lever positioning spring,

FIG. 5 is a view in section taken along the line 5-5 shown in FIG. 1,

FIG. 6 is a view in section taken along the line 6-6 shown in FIG. 1,

FIG. 7 is a rear view of the mounting plate with a portion broken away to show the adjustable bracket,

FIG. 8 is a view in elevation of a second embodiment of the interlock mechanism of this invention showing one of three associated switches in closed position, and

FIG. 9 is a view in elevation of the interlock mechanism of FIG. 8 showing its position when a different one of the three associated switches is closed.

Referring now to FIGS. 1-5, there is shown therein a pair of identical electromagnetically actuated switches A. and B which are attached to a common mounting plate 1. Like reference numerals are used in the drawings to designate like portions of the identical switches A and B, and for the purpose of this description reference will be made primarily to switch A. The switch A has a cast frame 2 upon which is mounted a switch hood assembly 3. The switch hood assembly 3 consists of a stationary contact enclosure 4 that is closed at the lower rear by an inner hood closure 5 and at the front by an outer hood closure 6. In FIG. 5 the side wall of enclosure 4 is broken away for illustration only. Extending downwardly through the top of the enclosure 4 is a first set of three front stationary contact terminals 7 and a second set of three rear stationary contact terminals 8 that are directly to the rear of the terminals 7. The rear terminals 3 rise above the terminals 7 for ease of connection with external wiring, and as shown in FIG. 5 the terminals 7 and 8 terminate at their lower ends in stationary contacts 9 and It) respectively.

Disposed beneath each pair of stationary contacts 9 and 16 is a movable bridging contact 11 that is held in a cage 12 and urged upwardly by a bias spring 13 to insure proper contact pressure between the stationary and movable contacts when the switch A is in closed position.

The cages 12 are integral parts of a vertically movable molded actuator 14 and they project upwardly from a horizontal cross bar portion 15. As shown in FIG. 5 the crossbar portion 15 is characterized by a horizontal ledge 16 extending across its rear which acts as a bearing surface for the interlock mechanism to be hereinafter described. The crossbar portion 15 also has a horizontal front ledge 1'7, and extending downwardly from each end of the crossbar 15 is a side arm 18. The two side arms 18 are joined together at their lower ends by a foot portion 19, and the actuator 14 is thus formed so as to encircle an area bounded at the top by the crossbar 15, at the sides by the arms 18 and at the bottom by the foot portion 19.

Within the area bounded by the actuator 14 is an electromagnet comprising a stationary laminated yoke 20, a movable laminated armature 21 and a coil 22.

The yoke 20 and armature 21 comprise a magnet to furnish the motor action for closing the switch A. The yoke 20 is U shaped, as viewed in FIG. 5, and is slotted across its top to receive a thin, rectangular mounting member 23. The ends of the member 23 overhang from the sides of the yoke 20, as seen in FIGS. 1 and 4, and are retained in cooperating notches in the cast frame 2, thereby holding the yoke 21) in a stationary position. The armature 21 is securely held within the foot portion 19 of the actuator 14, and as viewed in FIG. is also of a U shape to match the configuration of the yoke 20. The ends of the armature 21 are in facing relation to the ends of the yoke 20 to provide a pair of working gaps for the electromagnet whereby the armature will move toward and away from the yoke to furnish the motor action for closing and opening the switch A.

The coil 22 is supported at its rear by insertion within a recess 24 of the frame 2 and at the forward end it is held in an opening 25 of a front cap 26. The coil 22 is composed of a first winding 27 surrounding one of the working gaps of the electromagnet and a second winding 25 surrounding the other working gap. The windings 27 and 28 are encased in insulating material which makes up the body of the coil 22. The front cap 26 includes a small auxiliary contact housing 29 which contains control circuit contacts, not shown, that are operated by a lever 3h extending over the front crossbar ledge 17, as shown in FIG. 5.

The foregoing brief description of the switch A is not intended as a detailed recital of its construction, but rather to provide an illustration of one form of device with which the interlock of the invention may be employed. The operation of the switch is such that when the coil 22 is deenergized the armature 21 will be in the lower position of FIGS. 1, 3, 4 and 5. The actuator 14, which moves in unison with the armature 21, is also in the lower position so that the movable bridging contacts 11 are in open position with respect to the stationary contacts 9 and 111. The lower position of the actuator 14 is determined by engagement with a pair of posts 31 that form a part of the frame 2, and are shown in FIGS. 1 and 4, and this position of the actuator 14 also dictates the lower position of the armature 21.

Upon energization of the coil 22 the armature 21 is attracted upward toward the stationary yoke 21). Movement of the armature 21 into a sealed position with the yoke 21 carries the actuator 14 in an upward path of travel and the movable bridging contacts 11 are hence brought into engagement with the contacts 9 and 10. By way of illustration the upper, or energized position for an armature 21 and actuator 14 is depicted by dotted lines for switch B.

Turning now to the interlock between switches A and B, a rocker 32, which may be made of nylon, Delrin, or other suitable material is pivotally supported on a shaft 33 afixed at one end to a U-shaped outwardly extending portion 34 of a vertically adjustable bracket 35 (see FIGS. 6 and 7). An upper leg 36 of the U-shaped portion 34 extends through a slot 37 provided in the mounting plate 1 and terminates in an upwardly bent ear 38 that is directly behind the plate 1. The leg 36 is snugly received at its side edges by the slot 37 for guided vertical movement and it is prevented from leaving the slot 37 by the presence of the ear 3%. A lower leg 39 of the U-shaped portion 34 turns downwardly and merges into a downwardly extending vertical mounting portion 411 which is provided at its bottom end with a horizontal rearwardly bent finger 41 received for vertical guidance within a slot 42 of the mounting plate l. The bracket 35 is adjustably secured to the mounting plate 1 by a pair of screws 43 that pass through vertically elongated holes 44 without mounting portion 411 of the bracket 35 and are in threaded engagement with the plate 1. An adjustment stud 45 is journalled through a hole 46 disposed between the elongated holes 44 and has an eccentric 47 secured to it at its end. The stud 45 is free to rotate and the eccentric 47 rides within a horizontally elongatedslot 48 provided in the mounting frame 1.

The rocker 32 is provided with a pair of bearing surfaces or tracks 49 and 50. Engaged by the tracks 49 and 50 are rollers 51 and 52 respectively, each of which is rotatably secured to a respective adjacent track-follower end of a pair of levers 53 and 54. The levers 53 and 54 are supported intermediate their ends on shafts 55 which in turn are rotatably borne within hollow quill shafts 56 secured to the mounting frame 1. The lever 53 is provided with an outwardly bent lug 57 at its free end. In a like manner, the lever 54 has an outwardly bent lug 5%. Each of the lugs 57 and 58 are preferably curved in their transverse direction.

The interlock mechanism also includes lever positioning springs 91 and 92 for the levers 53 and 54, respectively (see FIG. 4). The springs 91 and 92 include hook arms 93 and 94, respectively, and restraining arms and 96, respectively, which arms extend from opposite ends of coiled spring bodies that are placed about the two lever shafts 55. The hook arms 93 and 94 engage the upper surfaces of the levers 53 and 54, respectively, to urge the free ends 57, 58 downwardly against the switch actuators. The restraining arms 95 and Q6 abut against the side faces of the cast frames 2 of switches A and B, as shown in FIGS. 3 and 4. The springs 91 and 92 are adapted to retain the lugs 57 and 58 against the ledges 16 for any position of the actuators 14 and are, therefore, designed to exert only the force required to counteract the weight of the associated levers. The use of the springs 91 and 92 increases the life of the interlock mechanism by decreasing the wear between the tracks 49, 50 and rollers 51, 52.

The operation of the interlock mechanism of this invention is as follows: A

The lugs 57 and 58 of the levers 53 and 54 are held against the respective ledges 16 in all switch positions by the action of the springs 51 and 92 which bear downwardly against the upper edges of the levers 53 and 54. It is necessary that the rocker 32 be adjusted to properly position the same with respect to the levers 53 and 54 so that with one switch closed, the other switch will be held down and open except for adequate clearance to insure that the closed switch will not be subjected to an opening force. Thus, if the rocker 32 is positioned too high relative to the levers 53 and 54, closing of switch B and the resulting rotation of the rocker 32 would force the lug 5'7 of the lever 53 against the ledge 16 of switch A with such force that the lever 53 would respond by attempting to rotate the rocker 32 counterclockwise thereby placing an opening force on the switch B through the lever 54. The proper vertical adjustment of the rocker 32 is achieved by first loosening the screws 43 and then turning the stud 45 in an amount dependent upon the extent and direction of adjustment desired. Turning the stud 45 will cause the eccentric 47 to rotate within the horizontally elongated slot 48 thereby raising or lowering the bracket 35. Once the desired adjustment has been obtained, the screws 43 are tightened to secure the bracket 35 in set position.

When it is desired to close switch B, the coil 22 is energized, thereby causing the armature 21 to move upward into sealed position against the yoke 20. Since the armature 21 is aflixed to the actuator 14, the actuator 14 will slide upwardly in a path dictated by the posts 31. This upward movement will cause the movable bridging contact 11 to make contact with the stationary contacts 9 and 10, thereby closing the switch. Since the lug 58 of the lever 54 is in the path of travel of the actuator 14, the ledge 16 of the switch B will contact the lug 58, thereby forcing the free end of lever 54 to rotate in a counterclockwise direction about the respective shaft 55. The roller 52 will exercise a camming action by rolling over the track 50, thereby rotating the rocker 32 in a clockwise direction. Since the lug 57 of the lever 53 is held against the ledge 16 of switch A by the spring 91, this rotation of the rocker 32 will prevent the lever 53 from rotating clockwise by the engagement of the track 49 with the roller 51 of the lever 53, thereby preventing the actuator 14 of switch A from moving upward into closed position.

The action of the levers 53 and 54 upon the rocker 32 results in a non-linear relationship which equates a large motion in the upper portion of the travel of one switch to a smaller motion in the lower portion of travel of the other switch. Thus, as switch A moves downward from closed position while switch B is moving upward into closed position, a small initial upward movement of the actuator 14 of switch B will result in a relatively large downward shift of the blocking position of the lug 57 of the lever 53. This non-linearity provides a greater gap between the disengaging contacts of one switch before contacts of the other switch can engage than is possible with linear motion interlocks. Furthermore, energizing one switch in the open position applies a force to open the other switch which is in closed position and does not result in a binding or jamming action as found in interference type interlocks.

When it is desired to close switch A, switch B must first be opened. Opening switch B is accomplished by deenergizing the coil 22 thereby releasing the armature 21 from the yoke 20 which allows the actuator 14 of switch B to fall downward into open position. Release of the actuator 14 of switch B permits the lug 57 of the lever 53 to be moved upward by the then unrestrained actuator 14 of the switch A when switch A is closed. The small initial upward movement of the lug 57 is translated into a larger downward movement of the lug 58 during the initial travel, thereby assuring the disengagement of the stationary and movable contacts of switch B prior to complete closure of switch A. The closing of switch A, with its attendent upward movement of the actuator 14, will prevent the lever 54 from rotating counterclockwise by engagement of the track 50 with the roller 52 thereby preventing switch B from being closed.

It will be noted that the interlock mechanism of this invention provides positive protection against the closing of one switch while the other switch is closed.

When it is necessary to employ three switches, only one of which may be closed at any one time, a linked interlock mechanism may be employed. Referring to FIGS. 8 and 9, three electromagnetically actuated switches C, D and E are attached to a suitable common mounting plate 59. Each of the switches C, D and E are identical with switches A and B described hereinbefore, and in the drawings, like reference numerals have been used to indicate like portions. A rocker 60 is disposed between switches C and D and a second rocker 61 is disposed between switches D and E. Each of the rockers 60 and 61 is rotatably supported upon a shaft 62 which is afiixed at its end to an outwardly extending portion of a respective adjustable brackets 63 and 64. The adjustable brackets 63 and 64 are identical in construction and operation to the adjustable bracket 35 hereinbefore described. The brackets 63 and 64 are provided with respective adjustment studs 65 and 66. Affixed to each of the studs 65 and 66 is an eccentric 67 which rides in a horizontally elongated slot of the mounting plate 59 (not shown), similar to slot 48.

The rocker 60 is provided with a pair of bearing surfaces or tracks 68 and 69, and the rocker 61 has similar tracks 70 and 71. Engaged by the tracks 68 and 69 are rollers 72 and 73, each of which is rotatably secured to a respective adjacent track follower end of a pair of levers 74 and 75. In a similar manner, rollers 76 and 77, rotatably secured to a pair of levers 78 and 79, are engaged by respective tracks 70 and 71 of rocker 61. Each of the levers 74, 75, 78 and 79 are pivotally supported intermediate their respective ends on shafts 80 secured at one end to the mounting plate 59. The levers 74 and 75 are provided at their free ends with outwardly bent lugs 81 and 82, respectively, and levers 78 and 79 have similar lugs 83 and 84, respectively. Each of the lugs 81, 82, 83 and. 84 are preferably curved in their transverse direction. A pair of lever positioning springs 97 and 93 are provided for each pair of levers 74 and 75, and 78 and 79 (see FIG. 9). The springs 97 and 98 are similar in construction and operation to the springs 91 and 92, and are positioned about respective shafts 80.

A linkage member 85 has pins 86 and 87 secured to its ends. The pins 86 and 37 are journaled in elongated slots 8'8 and 89 of the rockers and are provided with suitable axial retaining means 96 at their free ends. Each of the slots 88 and 89 have a width greater than the diameter of the pins 86 and 87 so that the pins can slide within the limits of the respective slots 88 and 89.

Prior to operation of the interlock mechanism of FIGS. 8 and 9, it is necessary to vertically position the adjustable brackets 63 and 64 so that when any one switch is closed the other switches are held in the down position except for adequate clearance to insure that the closed switch is not subjected to an opening force. The brackets 63 and 64 are adjusted vertically by turning adjustment studs 65 and 66 with the resulting effect previously described for bracket 35.

The interlock mechanism of FIGS. 8 and 9 will insure that only one of the switches C, D and E can be closed at any one time. Thus, when switch C is closed, the closure is effected by the attraction of the armature 21 to the yoke 20 thereby causing the actuator 14 to move upward to engage the movable bridging contact 11 with the stationary contacts 9 and 10. The upward travel of the actuator 14 of switch C will force the lug 81 upward, thereby causing lever 74 to rotate clockwise about its support (see FIG. 9). The roller 72 will exercise a camming action on the rocker 60, by engagement with the track 68, rotating the rocker 60 in a counterclockwise direction. The rotation of rocker 60 will cause its track 69 to engage the roller 73 thus holding the lug 82 of the lever 75 firmly in position over the ledge 16 of switch D thereby preventing the upward movement of the actuator 14 of switch D.

Switch E is also prevented from closing by the action of the linkage member on the rocker 61. The counterclockwise rotation of the rocker 60 caused by the closing of switch C will pull the linkage member 85 laterally toward switch C by the engagement of the pin 86 with a side of the slot 88 of rocker 60. This movement of the linkage member 85 will rotate the rocker 61 in a counterclockwise direction by the pin 87 contacting a side of the slot 89. The track 71 will then engage the roller 77 to prevent counterclockwise rotation of the lever 79 thereby preventing upward movement of actuator 14 of switch E.

If it should be desired to close switch D, switch C must first be opened to free lugs 82 and 83 from engagement with the ledge 16 of switch D. Switch D can then be closed by energizing its coil 22 causing its actuator 14 to move upward by thhe attraction of the armature 21 to the yoke 20 (see FIG. 8). The upward movement of the actuator 14 of switch D will force the lugs 82 and 83 upward, thereby causing lever 75 to rotate counterclockwise and lever 78 to rotate clockwise. The counterclockwise rotation of lever 75 will cause the track 68 to engage the roller 72 thus holding the lug 31 of the lever 74 firmly in position over ledge 16 of switch C, and will cause the track 71 to engage the roller 77 thus holding the lug 84 in position over the ledge 16 of switch E. Therefore, while switch D is closed, switches C and E cannot be closed.

t will also be apparent from the above description that switch E cannot be closed unless switches C and D are both open; and that when switch E is closed, the interlock mechanism of this invention will prevent the closure of switches C and D.

From the foregoing description it will be seen that the interlock mechanism of this invention is simple in design and construction, and may be assembled without direct connection with associated switches and without alteration of the switches. It will also be seen that the mechanical interlock is adjustable vertically for proper positioning relative to the associated switches, and that by providing suitable linkage means the interlock may be employed with a plurality of electromagnetic contactors.

We claim:

1. In a mechanical interlock for a pair of spaced electromagnets, wherein each has an operating magnet and an actuator movable in response to energization and deenergization of the magnet, the combination comprising: a rocker mounted between said electromagnets and having a pair of bearing tracks each displaced upon shift of the rocker to tilt at a varying angle of inclination with such shift; and a pair of levers spaced from one another and disposed at opposite portions of the rocker, each lever being pivoted to have a free end disposed away from the rocker in the path of travel of an actuator, and which free end is separate and relatively displaceable from such actuator, and a track follower end adjacent the rocker that swings in an are that intercepts one of said rocker tracks, to have such rocker track intercept the are at changing points along the are as the rocker shifts its position, whereby a rotation of one lever, by movement of the operatively associated actuator in response to energization of its magnet, engages the track follower end of such lever against a bearing track to shift the rocker into a position limiting the rotation of the second lever.

2. In an interlock for a pair of electromagnets that are spaced from one another, wherein each has an operating magnet and an actuator movable in response to energization and deenergization of the magnet, the combination comprising: a pivotally mounted rocker between said electromagnets, said rocker having a pair of bearing surfaces that rotate about the pivot of the rocker as the rocker is turned on its mounting to thereby change the angle of inclination of each bearing surface with a change in rocker position; a first pivoted lever for said rocker which has a follower end disposed to engage one of said bearing surfaces and a free end in the path of travel of one magnet actuator, said free end being separate and relatively displaceable from such actuator, whereby the actuator moving in response to energization of its associated magnet contacts the free end of said first lever to pivot the follower'end of said lever against such rocker bearing surface to tilt the same, and whereby an opposite tilt of such rocker bearing surface toward the lever follower end blocks rotation of the first lever to prevent the actuator from moving in response to energization of its associated magnet; and a second pivoted lever for said rocker which has a follower end disposed to engage the other of said bearing surfaces and a free end in the path of travel of a second magnet actuator, said free end being separate and relatively displaceable from such actuator, whereby the actuator moving in response to energization of its associated magnet contacts the free end of said second lever to pivot the follower end of said lever against such rocker bearing surface to tilt the same, and whereby an opposite tilt of such rocker bearing surface toward the lever follower end blocks rotation of the second lever to prevent the second actuator from moving in response to energization of its associated magnet.

3. In an interlock for a pair of electromagnets that are spaced from one another, wherein each has an operating magnet and an actuator movable in response to energization and deenergization of the magnet, the combination comprising: a pivotally mounted rocker between said electromagnets, said rocker having a pair of bearing surfaces that rotate about the pivot of the rocker as the rocker is turned on its mounting to thereby change the angle of inclination of each bearing surface with a change in rocker position; a first pivoted lever for said rocker which has a follower end disposed to engage one of said bearing surfaces and a free end in the path of travel of one magnet actuator, said free end being separate and relatively displaceable from such actuator, whereby movement of the actuator in response to energization of its associated magnet pivots the follower end of said lever against such rocker bearing surface to tilt the same, and

whereby an opposite tilt of such rocker bearing surface toward the lever follower end blocks rotation of the first lever to prevent the actuator from moving in response to energization of its associated magnet; a second pivoted lever for said rocker which has a follower end disposed to engage the other of said bearing surfaws and a free end in the path of travel of a second magnet actuator, said free end being separate and relatively displaceable from such actuator, whereby movement of the actuator inrespouse to energization of its associated magnet pivots the follower end of said lever against such rocker bearing surface to tilt the same, and whereby an opposite tilt of such rocker bearing surface toward the lever follower end blocks rotation of the second lever to preventthe second actuator from moving in response to energization of its associated magnet; and lever positioning springs engaging each lever and adapted to retain the free ends of the levers in contact with their operatively associated actuators in all actuator positions. 7

4. In an interlock for a plurality of electromagnets that are spaced from one another, wherein each has an operating magnet and an actuator movable in response to energization and deenergization of the magnet, the combination comprising: a pivotally mounted rocker between said electromagnets, each rocker having a pair of bearing surfaces that rotate about the pivot of the rocker as the rocker is turned on its mounting to thereby change the angle of inclination of each bearing surface with a change in rocker position; a first pivoted lever for each rocker which has a follower end disposed to engage one of said bearing surfaces and a free end in the path of travel of one magnet actuator, said free end being separate and relatively displaceable from such actuator, whereby the actuator moving in response to energization of its associated magnet contacts the free end of said first lever to pivot the follower end of saidlever against such rocker bearing surface to tilt the same, and whereby an opposite tilt of such rocker bearing surface toward the lever follower end blocks rotation of the first lever to prevent the actuator from moving in response to energization of its associated magnet; a second pivoted lever for each rocker which has a follower end disposed to engage the other of said bearing surfaces and a free end in the path of travel of a second magnet actuator, said free end being separate and relatively displaceable from such actuator, whereby the actuator moving in response to energization of its associated magnet contacts the free end of said second lever to pivot the follower end of said lever against such rocker bearing surface to tilt the same, and whereby an opposite tilt of such rocker bearing surface toward the lever follower end blocks rotation of the second lever to prevent the second actuator from moving in response to energization of its associated magnet; and a linkage member joining each adjacent pair of rockers adapted to provide the same direction of inclination to the bearing surfaces of all rockers disposed to one side of an actuator responding to energization of its associated magnet and also to provide the same direction of inclination to the bearing surfaces of all rockers disposed to the other side of such actuator.

5. In an interlock for a pair of electromagnets that are spaced from one another and attached to a common base plate, wherein each has an operating magnet and an actuator movable in response to energization and deenergization of the magnet, the combination comprising: a pivotally mounted rocker between said electromagnets, said rocker having a pair of bearing surfaces that rotate about the pivot of the rocker as the rocker is turned on its mounting to thereby change the angle of inclination of each bearing surface with a change in rocker position; a first pivoted lever for said rocker which has a follower end disposed to engage one of said bearing surfaces and a free end in the path of travel of one magnet actuator, said free end being separate and relatively displaceable from such actuator, whereby the actuator moving in response to energization of its associated magnet contacts 9 the free end of said first lever to pivot the follower end of said lever against such rocker bearing surface to tilt the same, and whereby an opposite tilt of such rocker bearing surface toward the lever follower end blocks rotation of the first lever to prevent the actuator from moving in response to energization of its associated magnet; a second pivoted lever for said rocker which has a follower end disposed to engage the other of said bearing surfaces and a free end in the path of travel of a second magnet actuator, said free end being separate and relatively displaceable from such actuator, whereby the actuator moving in response to energization of its associated magnet contacts the free end of said second lever to pivot the follower end of said lever against such rocker bearing surface to tilt the same, and whereby an opposite tilt of such rocker bearing surface toward the lever follower end blocks rotation of the second lever to prevent the second actuator from moving in response to energization of its associated magnet; and adjustment means mounting said rocker and in slidable contact with the base plate, adapted to move said rocker generally parallel to the direction of travel of the magnet actuators and retain the rocker in set position.

6. The interlock of claim 5 wherein the adjustment means is comprised of: a mounting plate guided at its ends in respective slots in the base plate, said mounting plate having an outwardly extending portion spaced from said base plate and adapted to mount an associated rocker and also having a flat portion in surface contact with said base plate; an eccentric member journaled through said flat portion, riding in a cooperating slot in said base plate whereby rotation of said eccentric member will be translated into linear movement of said mounting plate; and means for retaining the mounting plate in set position.

7. In an interlock for a pair of spaced vertically movable switch actuators the combination comprising: a rocker for disposition between said switch actuators that is free to swing in a substantially vertical plane toward and away from each of the switch actuators and which has bearing track surfaces at its opposite sides whereby swinging movement toward an actuator raises one track surface and lowers the other; a first lever disposed between said rocker and one of said switch actuators pivoted between its ends to turn in a plane substantially parallel to that of the swinging motion of said rocker, one of the lever ends being a free end intercepting the path of travel of the adjacent switch actuator to be contacted and raised by upward movement of the actuator and to block such upward movement when it is held depressed, said free end being separate and relatively displaceable from such actuator, the other lever end being a track surface follower disposed to intersect a track surface of said rocker and to be at an elevation opposite that of the free end; and a second lever disposed between said rocker and the other of said switch actuators that is similarly pivoted between its ends to turn in a plane substantially parallel to that of the swinging motion of the rocker, one of the lever ends of the second lever being a free end intercepting the path of travel of the adjacent switch actuator to be contacted and raised by upward movement of said actuator and to block upward actuator movement when it is held depressed, said free end being separate and relatively displaceable from such actuator, the other end of said second lever being a track surface follower disposed to intersect the second track surface of said rocker and to be at an elevation opposite that of the free end; upward travel of one switch actuator thereby raising the free end of the associated lever to depress the follower end of said lever to place said rocker in a position engaging the follower end of the other lever thereby preventing rotation of such other lever to block upward movement of thesecond switch actuator.

8. An interlock in accordance with claim 7 wherein said levers are pivotally attached to a plate adapted to receive said switch actuators and there being a bracket mounted upon and vertically movable with respect to said plate, said bracket mounting said rocker for vertical adjustment of the rocker position, and there being provided locking means for holding said bracket in position with respect to said plate.

References Cited in the file of this patent UNITED STATES PATENTS 2,425,190 Johnson et al Aug. 5, 1947 2,640,116 Dyer et a1. May 26, 1953 2,722,135 Taylor Nov. 1, 1955 2,756,612 Schleicher July 31, 1956 

1. IN A MECHANICAL INTERLOCK FOR A PAIR OF SPACED ELECTROMAGNETS, WHEREIN EACH HAS AN OPERATING MAGNET AND AN ACTUATOR MOVABLE IN RESPONSE TO ENERGIZATION AND DEENERGIZATION OF THE MAGNET, THE COMBINATION COMPRISING: A ROCKER MOUNTED BETWEEN SAID ELECTROMAGNETS AND HAVING A PAIR OF BEARING TRACKS EACH DISPLACED UPON SHIFT OF THE ROCKER TO TILT AT A VARYING ANGLE OF INCLINATION WITH SUCH SHIFT; AND A PAIR OF LEVERS SPACED FROM ONE ANOTHER AND DISPOSED AT OPPOSITE PORTIONS OF THE ROCKER, EACH LEVER BEING PIVOTED TO HAVE A FREE END DISPOSED AWAY FROM THE ROCKER IN THE PATH OF TRAVEL OF AN ACTUATOR, AND WHICH FREE END IS SEPARATE AND RELATIVELY DISPLACEABLE FROM SUCH ACTUATOR, AND A TRACK FOLLOWER END ADJACENT THE ROCKER THAT SWINGS IN AN ARC THAT INTERCEPTS ONE OF SAID ROCKER TRACKS, TO HAVE SUCH ROCKER TRACK INTERCEPT THE ARC AT CHANGING POINTS ALONG THE ARC AS THE ROCKER SHIFTS ITS POSITION, WHEREBY A ROTATION OF ONE LEVER, BY MOVEMENT OF THE OPERATIVELY ASSOCIATED ACTUATOR IN RESPONSE TO ENERGIZATION OF ITS MAGNET, ENGAGES THE TRACK FOLLOWER END OF SUCH LEVER AGAINST A BEARING TRACK TO SHIFT THE ROCKER INTO A POSITION LIMITING THE ROTATION OF THE SECOND LEVER. 